This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:    3GPP third generation partnership project    ACK acknowledge    BS base station    BW bandwidth    CA carrier aggregation    CC component carrier    CCE control channel element    DAI downlink assignment index    DL downlink (eNB towards UE)    eNB E-UTRAN Node B (evolved Node B)    EPC evolved packet core    E-UTRAN evolved UTRAN (LTE)    FDMA frequency division multiple access    HSPA high speed packet access    IMTA international mobile telecommunications association    ITU-R international telecommunication union-radiocommunication sector    LTE long term evolution of UTRAN (E-UTRAN)    LTE-A LTE advanced    MAC medium access control (layer 2, L2)    MM/MME mobility management/mobility management entity    NACK not (negative) acknowledge    NodeB base station    OFDMA orthogonal frequency division multiple access    O&M operations and maintenance    PDCCH physical downlink control channel    PDCP packet data convergence protocol    PHY physical (layer 1, L1)    PUCCH physical uplink control channel    PUSCH physical uplink shared channel    QPSK quadrature phase shift keying    Rel release    RLC radio link control    RRC radio resource control    RRM radio resource management    SGW serving gateway    SC-FDMA single carrier, frequency division multiple access    TDD time division duplex    UE user equipment, such as a mobile station, mobile node or mobile terminal    UL uplink (UE towards eNB)    UPE user plane entity    UTRAN universal terrestrial radio access network
One modern communication system is known as evolved UTRAN (E-UTRAN, also referred to as UTRAN-LTE or as E-UTRA). In this system the DL access technique is OFDMA, and the UL access technique is SC-FDMA.
One specification of interest is 3GPP TS 36.300, V8.11.0 (2009-12), “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Access Network (EUTRAN); Overall description; Stage 2 (Release 8),” incorporated by reference herein in its entirety. This system may be referred to for convenience as LTE Rel-8. In general, the set of specifications given generally as 3GPP TS 36.xyz (e.g., 36.211, 36.311, 36.312, etc.) may be seen as describing the Release 8 LTE system. More recently, Release 9 versions of at least some of these specifications have been published including 3GPP TS 36.300, V9.3.0 (2010-03).
FIG. 1A reproduces FIG. 4.1 of 3GPP TS 36.300 V8.11.0, and shows the overall architecture of the EUTRAN system (Rel-8). Reference can also be made to FIG. 1B. The E-UTRAN system includes eNBs, providing the E-UTRAN user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towards the UEs. The eNBs are interconnected with each other by means of an X2 interface. The eNBs are also connected by means of an S1 interface to an EPC, more specifically to a MME by means of a S1 MME interface and to a S-GW by means of a S1 interface (MME/S-GW 4). The S1 interface supports a many-to-many relationship between MMEs/S-GWs/UPEs and eNBs.
The eNB hosts the following functions:
functions for RRM: RRC, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UEs in both UL and DL (scheduling);
IP header compression and encryption of the user data stream;
selection of a MME at UE attachment;
routing of User Plane data towards the EPC (MME/S-GW);
scheduling and transmission of paging messages (originated from the MME);
scheduling and transmission of broadcast information (originated from the MME or O&M); and
a measurement and measurement reporting configuration for mobility and scheduling.
Of particular interest herein are the further releases of 3GPP LTE (e.g., LTE Rel-10) targeted towards future IMTA systems, referred to herein for convenience simply as LTE-Advanced (LTE-A). Reference in this regard may be made to 3GPP TR 36.913, V9.0.0 (2009-12), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Requirements for Further Advancements for E-UTRA (LTE-Advanced) (Release 9). Reference can also be made to 3GPP TR 36.912 V9.3.0 (2010-06) Technical Report 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Feasibility study for Further Advancements for E-UTRA (LTE-Advanced) (Release 9).
A goal of LTE-A is to provide significantly enhanced services by means of higher data rates and lower latency with reduced cost. LTE-A is directed toward extending and optimizing the 3GPP LTE Rel-8 radio access technologies to provide higher data rates at lower cost. LTE-A will be a more optimized radio system fulfilling the ITU-R requirements for IMT-Advanced while keeping the backward compatibility with LTE Rel-8.
As is specified in 3GPP TR 36.913, LTE-A should operate in spectrum allocations of different sizes, including wider spectrum allocations than those of LTE Rel-8 (e.g., up to 100 MHz) to achieve the peak data rate of 100 Mbit/s for high mobility and 1 Gbit/s for low mobility. It has been agreed that carrier aggregation is to be considered for LTE-A in order to support bandwidths larger than 20 MHz. Carrier aggregation, where two or more component carriers (CCs) are aggregated, is considered for LTE-A in order to support transmission bandwidths larger than 20 MHz. The carrier aggregation could be contiguous or non-contiguous. This technique, as a bandwidth extension, can provide significant gains in terms of peak data rate and cell throughput as compared to non-aggregated operation as in LTE Rel-8.
A terminal may simultaneously receive one or multiple component carriers depending on its capabilities, A LTE-A terminal with reception capability beyond 20 MHz can simultaneously receive transmissions on multiple component carriers. A LTE Rel-8 terminal can receive transmissions on a single component carrier only, provided that the structure of the component carrier follows the Rel-8 specifications. Moreover, it is required that LTE-A should be backwards compatible with Rel-8 LTE in the sense that a Rel-8 LTE terminal should be operable in the LTE-A system, and that a LTE-A terminal should be operable in a Rel-8 LTE system.
FIG. 1C shows an example of the carrier aggregation, where M Rel-8 component carriers are combined together to form MHRel-8 BW (e.g. 5 H 20 MHz=100 MHz given M=5). Rel-8 terminals receive/transmit on one component carrier, whereas LTE-A terminals may receive/transmit on multiple component carriers simultaneously to achieve higher (wider) bandwidths. It has been agreed that up to five CCs can be aggregated in LTE-Advanced in both the FDD and TDD systems.
FIG. 1D depicts the use of aggregate component carriers in terms of the system bandwidth. In FIG. 1D, the total system bandwidth is shown as 100 MHz (frequency). In Case 1, a first case for LTE-A with aggregated component carriers, all of this bandwidth is aggregated and used by a single UE device. In case 2, the bandwidth is partially aggregated into two 40 MHz groups, leaving a 20 MHz grouping. This remaining bandwidth may be used, for example, by a Release 8 LTE UE, which only requires 20 MHz. It should be noted that the CA configuration is UE specific, which means that that Rel-8 UEs can operate in each of the five carriers shown. In Case 3 none of the CCs are aggregated and thus five 20 MHz components are available for use by five different UEs.
3GPP TS 36.211 V9.1.0 (2010-03) Technical Specification 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 9) describes in Section 5.4.1 the PUCCH formats 1, 1a and 1b.
In LTE Rel-8 TDD the UE has the possibility to report ACK/NACK feedback associated with multiple DL subframes during one UL subframe. Hence, the ACK/NACK resources corresponding to multiple DL subframes are reserved on the corresponding UL subframe in an implicit manner (i.e., based on the mapping between ACK/NACK resources and the first CCE of the corresponding PDCCH). Explicit PUCCH resource allocation is applied for a persistently scheduled PDSCH.
For the LTE-Advanced system it has been agreed in 3GPP RAN1#58bis to support the mapping of ACK/NACK resources on one UE-specific UL CC. For the LTE-Advanced TDD system this implies that multiple ACK/NACK resources (corresponding to multiple DL subframes in the time domain and multiple (DL) CCs in the frequency domain) need to be allocated on one UE-specific (UL) CC during a single UL subframe.
This approach can be expected to increase PUCCH resource allocation/consumption on the UE-specific UL CC. From a resource consumption point of view it would be desirable to provide an efficient PUCCH format 1a/1b resource allocation for LTE-Advanced TDD.